1. Field of the Invention
This invention relates to abradable materials useful in high operating temperature sealing members. The new and improved materials described herein below are particularly useful as sealing surfaces between adjacent rotating and stationary elements of turbomachines, such as compressors and turbines, which operate at elevated temperatures.
2. Description of the Prior Art
As is well known in the art, the efficiency of gas turbine engines is dependent in part on the peripheral seal between the ends of the rotor and stationary blades, and the adjacent engine structure. The use of abradable sealing materials is well known and a number of different methods have been proposed for employing such materials. See for example, U.S. Pat. No. 3,413,136, wherein an abradable porous nickel sealing surface is formed on affected engine parts by a spray technique. U.S. Pat. No. 3,519,282 shows an abradable, porous, metal fiber seal wherein the pores are filled with copper and/or nickel powder. The advantages of metal fiber seals are set forth therein in some detail. Porous metal seals are likewise employed for this purpose, as is shown for example by U.S. Pat. No. 3,268,997 and 3,350,178. However, it has been found that due to high temperatures involved, oxidation of the seals employed heretofore can occur, lessening the sealing capability and lowering efficiency.